Single and multi-track, magnetic stripe encoders are in widespread commercial use. Such encoders are adapted to write on selected tracks on the stripe depending on the design and position of the write head. Writing occurs by the activation and positioning of a single gap write head with respect to the selected track and by the activation of the coil corresponding to the selected gap of a single or multi-gap write head corresponding to the track(s) to be written.
Many encoders are table top motorized apparatus into which a card is inserted for encoding. With apparatus of this type, previously encoded data are on tracks adjacent to the track being encoded not exposed to the risk of being overwritten. This is not the case for hand swipe encoders, where the card is swiped manually through the encoder and card registration is accomplished by hand. In such cases the write head is positioned to encode on a magnetic track when the card is positioned in a vertical plane with its edge moving along a reference surface. Often the card is not seated properly against the reference surface when swiped and track misalignment results. Often, also, previously written data on a track adjacent to the selected track is destroyed.